Liverpool Hospital Bridge Approaches, NSW

Project featuring the KeySteel®, Keystone & Geogrid System.

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General Information

Daracon were contracted by ARTC to construct pedestrian and vehicular bridge widenings as part of the Southern Sydney Freight Line project. The job involved the construction of two bridge approaches within the grounds of Liverpool Hospital. The abutments were to support a vehicular access bridge across the rail line, which was under construction.

The two abutments: Abutment A (MW01& MW04, 100m long) & Abutment B (MW02 & MW03, 121m long) involved the design & construction of a 8.8 m high masonry concrete block reinforced soil walls using KeySteel®, Keystone Compac II, KeyStrip steel ladder & Miragrid polyester geogrid soil reinforcements. The wall was required to support a uniform vertical live load surcharge equivalent to 20kPa and dead loads from the reinforced concrete integrated crash barrier/pavement spanning both walls. The top course of Keystone Compac blocks were stepped @ 200mm to grade to cater for the final ramp profile. The concrete parapet covered the top 400mm of wall profile.

A key feature of this project was that an external scaffold to the wall face could not be used for fall protection due to tight boundary constraints, the alternative utilized an innovative fall from height system using vertical/horizontal scaffold poles secured internally to prevent workers falling from height during both block placement and hand compaction operations.

Both bridge abutment headstocks were piled using 900dia concrete piles surrounding by 1200mm dia corrugated duct sleeves. Where normal spacing of KeyStrip could not be used, additional layers were incorporated into the design. An additional wall was designed and constructed behind Abutment A to take subsequent loads off the abutment face. Cement stabilized sand and/or No-Fines concrete was used in areas where hand compaction could not be achieved. Where blocks extended up in front of the abutment headstock, N20 bars were incorporated into the facing column and filled with 32MPa concrete. Another innovative design solution carried out by Retaining Solutions.